The protohistoric period of the Korean peninsula, c 1-300 AD, which preceded the Three Kingdoms period of Koguryo, Silla, and the Paekche. Archaeological finds of the period are mainly from Lelang and Koguryo in the north and Samhan in the south. Bronze and iron were used and iron made at shell midden sites on the southern coast. In actuality, the Three Kingdoms period was c 57 BC-668 AD.